Composite grille louvers

ABSTRACT

A grille having a plurality of s-louvers shaped to increase the efficiency of air flow through the grille without decreasing the effectiveness of the louvers at stopping or deflecting projectiles. Each louver has a hooked portion at the end of the louver to present a ballistic hook for stopping projectiles ricocheting through the circuitous path defined between the louvers. An insert having a closeout for covering the ballistic hook is positioned within each hooked shape portion to eliminate the eddy or stall created at the end of the circuitous path by ballistic hook. The closeout can be penetrated by projectiles ricocheting through the circuitous path such that the ballistic hook can still capture projectiles within the inlet.

RELATED APPLICATION

The present application claims the benefit of U.S. ProvisionalApplication No. 61/467,605 entitled “COMPOSITE GRILLE LOUVERS, filedMar. 25, 2011, which is incorporated herein in its entirety byreference.

FIELD OF THE INVENTION

The present invention is generally directed to ballistic louverspermitting the flow of air through a vent while preventing projectilesfrom entering the vent. Specifically, the present invention is directedto ballistic louvers for improving air flow through the vent whilemaintaining ballistic projection.

BACKGROUND OF THE INVENTION

Armored vehicles often have intake exhaust vents for supplying air toengine components and other systems. However, if a projectile enters thevent, the projectile can damage the engine or other components. A grillehaving a plurality of louvers is commonly fitted to the intake exhaustvents to prevent projectiles from entering the engine compartment whilepermitting air to flow between the louvers into the protected area.Grilles typically comprise chevrons as shown in FIG. 1 or S-shapedlouvers as shown in FIG. 2 that are arranged in an overlappingconfiguration to define a series of circuitous paths through the vent.As most projectiles travel along a linear or nearly linear flight path,the projectiles cannot navigate the non-linear paths without contactingat least one louver. The louvers typically comprise materials such ashardened steel or monolithic aluminum that can deflect, fragment orcapture the projectiles. Although the projectiles cannot easily navigatethe non-linear paths defined by the louvers, air can easily flow throughthe non-linear paths.

The inherent tradeoff with a louver protected vent is that improvingprotection for the vent typically worsens the air flow through the vent.Increasing the number of louvers reduces the likelihood that aprojectile can successfully penetrate the vent, but also reduces thecross-sectional area through which the air can flow. While thecircuitous flow paths do not block the air flow, the supply of air tothe engine compartment can be slowed if the paths are too narrow. Theslowed air supply can hinder the performance of the engine componentssupplied by the vent. However, reducing the number of louvers toincrease the cross-sectional area of the circuitous paths increases thelikelihood that a projectile will penetrate the grille and enter theengine compartment.

A common feature of S-shaped louvers is a hook shaped portion, as shownin FIGS. 3-5 and as disclosed in U.S. Pat. No. 3,901,124, at the end ofeach louver to create an inlet and a ballistic hook at the end of thecircuitous path for capturing projectiles or fragments that may havericocheted through the circuitous path. The reference is herebyincorporated by reference in its entirety. The hooked shaped portionserves as a final defense against projectiles passing through the vent.However, the inlet and ballistic hook defined by the hooked shapedportion can create a stall or eddy in the air flow through thecircuitous path upsetting the smooth air flow through the grille andcreating a large pressure drop across the vent.

A similar tradeoff is that increasing the size or number of louvers canincrease the weight and profile of the grille. As disclosed in U.S. Pat.No. 5,753,847, a technique for improving the protective ability ofgrille is to position an applique of hardened steel bars in front of thelouvers to fragment the projectiles before the projectiles reaches thelouvers to reduce the impact of the projectile. The reference is herebyincorporated in its entirety. However, the drawback of the bars is thatthe bars significantly increase the weight and profile of the grill.

As such, there is a need for maintaining the protective ability of thegrille while improving the airflow through the circuitous path.Similarly, there is a need for improving the protective ability of thegrille while reducing or maintain the weight and profile of the grill.

SUMMARY OF THE INVENTION

The present invention is directed to a grille having louvers shaped toincrease the efficiency of air flow through the grille withoutdecreasing the effectiveness of the louvers at stopping or deflectingprojectiles. Each louver comprises an S-shape with a hooked portion atthe end of the louver to present a ballistic hook for stoppingprojectiles ricocheting through the circuitous path defined between thelouvers. An insert comprising a foam core and covered by a closeout ispositioned within each hooked shape portion. The insert fills in theinlet in the louver created by the hooked shape portion to define acontinuous S-shape to eliminate the eddy or stall created at the end ofthe circuitous path by the hooked shape portion. Alternatively, theinlet can be enclosed by the closeout to define an air pocket within theinlet. The closeout can be penetrated by projectiles ricocheting throughthe circuitous path such that the ballistic hook can capture theprojectile within the inlet.

A grille, according to an embodiment of the present invention, comprisesa plurality of S-shaped louvers arranged in an overlapping configurationto define a plurality of circuitous paths between the louvers throughthe grille. Each louver comprises a hooked shaped portion at one enddefining an inlet and a ballistic hook generally perpendicular to thecircuitous path. An insert comprising a foam core can be positionedwithin an inlet. The insert can be shaped to “fill in” the inlet toprevent the ballistic hook from creating eddies or stalls as air flowsthrough the circuitous path. The insert can further comprise a closeoutcomprising a material positioned over the foam core to provide acontinuous surface creating a smooth air flow. Alternatively, thecloseout can be positioned over the inlet with a foam core so as todefine an air pocket within the inlet.

In one aspect, a plurality of hardened bars can be positioned in frontof the louvers to fragment or degrade incoming projectiles before theprojectiles reach the louvers. Similarly, in one aspect, an openhoneycomb mesh can be positioned behind to capture the remainingprojectile fragments that ricochet through circuitous path and are notcaptured by the ballistic hooks of the louvers. In this aspect, thelouvers can comprise a low weight composite material to offset theincreased weight from the bars and mesh.

In one aspect, a method of preventing projectiles from entering a ventcomprising the steps of positioning a plurality of S-shaped louvers inthe vent, wherein each louver comprises a hook shape portion defining aninlet and a ballistic hook oriented to capture projectiles at one end ofthe louver. The method further comprises arranging the S-shaped louversin an overlapping arrangement to define a plurality of circuitous routesbetween the louvers for the passage of air through the vent. Finally,the method comprises positioning an insert within the inlet to enclosethe ballistic hook to prevent disruption of the air flow through thecircuitous path, wherein the insert comprises a lower density materialthan the louver such that the projectile can penetrate the insert and becaptured within by the ballistic hook.

The above summary of the various representative embodiments of theinvention is not intended to describe each illustrated embodiment orevery implementation of the invention. Rather, the embodiments arechosen and described so that others skilled in the art can appreciateand understand the principles and practices of the invention. Thefigures in the detailed description that follow more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE CLAIMS

The invention can be completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a cross-sectional side view of a prior art grille having aplurality of chevron shaped louvers.

FIG. 2 is a cross-sectional side view of a prior art grille having aplurality of S-shaped louvers.

FIG. 3 is a cross-sectional side view of a prior art grille having aplurality of S-shaped louvers each defining a hooked portion.

FIG. 4 is a cross-sectional side view of a prior art grille having aplurality of S-shaped louvers each defining a hooked portion.

FIG. 5 is a cross-sectional side view of a prior art grille having aplurality of S-shaped louvers each defining at least two hookedportions.

FIG. 6 is a rear view of a representative vehicle having a grilleaccording to an embodiment of the present invention.

FIG. 7 is an exploded perspective view of a grille according to anembodiment of the present invention.

FIG. 8 is a cross-sectional side view of a grille according to anembodiment of the present invention.

FIG. 9 is a partial perspective view of an inner end of a louveraccording to an embodiment of the present invention.

FIG. 10 is a representative cross-sectional side view of an arrangementof louvers according to an embodiment of the present inventionillustrating the flow of air through the louvers.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

As shown in FIGS. 6-9, a grille 10, according to an embodiment of thepresent invention, comprises a plurality of S-shaped louvers 12 eachhaving an exterior end 14 and an interior end 16. In one aspect, theexterior end 14 can comprise a tapered shape to minimize disruption ofthe airflow through the grille 10. The interior end 16 further comprisesa hooked portion 18 defining an inlet 20 in the louver 12 and aballistic hook 22 generally perpendicular to the louver 12. Each louver12 further comprises an insert 22 shaped to fit within the inlet 20 andcomprising a foam core 24 and a closeout 26. In another aspect, thelouver 12 can only comprise the closeout 26 to define an air pocket inthe inlet 20. In one aspect, the louvers can be about 3 inches long.

In one aspect, the louvers 12 can comprise a composite material ratherthan a metal to reduce the overall weight of the grille 10 whileimproving the ballistic protection of the grille 10. The compositematerial can capture projectiles with the same effectiveness as steel oraluminum at a fraction of the weight. The composite material cancomprise a non-woven fibrous material impregnated with a thermoplasticor thermoset resin matrix material. In one aspect, the fibrous materialcan comprise aramid (KEVLAR) or S2 glass fibers. In one aspect, thecomposite material can comprise 60-80 wt % fibrous material and 20-40 wt% matrix material. The composite material can formed by manufacturingprocesses including, but not limited to, pultrusion, hand lay-up orresin infusion methods.

Similarly, the foam core 24 can comprise a medium to high density closedcell foam having a lower density than the composite material used forthe body of the louver 12. In one aspect, the closeout 26 can comprisethe same composite material as the body of the louver 12.

As shown in FIGS. 8-10, the louvers 12 can be positioned in parallel todefine a plurality of circuitous paths between the louvers 12. Theexterior ends 14 of the louvers 12 are each oriented toward the exteriorof the vent into which the grille 10 while the interior ends 16 of thelouvers are oriented toward the vehicle compartment to be protected. Thecurved portions of the louvers 12 are positioned in an overlappingarrangement such that no linear path between the louvers 12 exists. Inone aspect, the louvers 12 can be positioned about 0.75 inches apart. Inanother aspect, the louvers 12 are nested such that the flow paththrough the grille 10 between the louvers 12 is about 50% of thecross-sectional area of the grille 10. Projectiles travelling along agenerally linear path cannot navigate between the louvers 12 withoutcontacting the louvers 12. The louvers 12 are shaped to deflect orcapture projectiles that contact the louver 12.

As shown in FIG. 10, air can navigate the circuitous path between thelouvers 12 and pass through the grille 10. The S-shaped louver 12provides a lower pressure drop across the louvers 12 than other shapes.The closeout 26 presents a continuous airfoil along the length of thelouver 12 such that eddies or stalls does not form at the end of thelouver 12 as a result of the inlet 20 and ballistic hook 22. Thecloseout 26 is sufficiently rigid to maintain the continuous airfoil asthe air travels between the louvers 12. If a projectile is deflecteddown the circuitous path, the lower density of the foam core 24 or theempty space of the air pocket allow the thin closeout 26 to bepenetrated by the projectile such that the projectile enters the inlet20 and is captured by the ballistic hook 22.

As shown in FIG. 8, in one aspect, the grille 10 can further comprise aplurality of hardened bars 28 in front of the exterior ends 14 of thelouvers 12. The hardened bars 28 can comprise a hardened metal or otherhardened material such that the bars 28 can fragment or otherwise erodethe projectiles before the projectiles reach the louvers 12. In oneaspect, the bars can be arranged in a 30 to 40 psf array.

As shown in FIG. 8, in one aspect, a honeycomb mesh 30 can be positionedbehind the interior ends 16 of the louvers 12. The honeycomb mesh 30 cancapture any remaining projectiles that survive ricocheting through thecircuitous paths. In particular, the mesh 30 can act as a filtercapturing small fragments of projectiles that have broken up passingthrough the louvers 12. The mesh 30 can be constructed of anylightweight material known in the art such as aluminum, ceramic,plastic, carbon fiber, or composite material.

In one aspect, the grille 10 can further comprise a frame 32 forsimplifying installation of the grille 10. The louvers 12 and mesh 30can be pre-bonded to the frame 32, while the bars 28 can be pre-weldedto the frame 32 such that the entire frame 32 can be installed into avehicle 11 as a single unit as shown in FIG. 6.

The grille 10 can be affixed to a plurality of armored vehicles 11including, but not limited to tanks, infantry fighting vehicles, armoredcars or self-propelled artillery. As depicted in FIG. 6, the grille 10is installed over the air supply vents for the engine of an M1A1 Abramstank. The figure is intended to be representative of the installation ofthe grille 10 and not intended to be limiting with regards to thevehicle 11 on which the grille 10 can be installed.

In one aspect of the present invention, a method of preventing aprojectile from entering a vent comprises positioning a plurality ofS-shaped louvers 12 in the vent, wherein each louver 12 defines an inlet20 and a ballistic hook 22. The method further comprises arranging theS-shaped louvers 12 in an overlapping arrangement to define a pluralityof circuitous paths between the louvers 12 allowing air to flow throughthe vent while denying projectiles a direct linear path through thevent. Finally, the method comprises positioning an insert 22 within theinlet 20 to cover the ballistic hook 22 and define a continuous s-shapealong the entire louver 12, wherein the insert 22 comprises a lowerdensity material than the louver 12 such that the projectile canpenetrate the insert 22 and be arrested by the ballistic hook 22.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and described in detail. It is understood, however, that theintention is not to limit the invention to the particular embodimentsdescribed. On the contrary, the intention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

1. A ballistic grille for preventing projectiles from entering a protected vehicle compartment through an air supply vent while allowing air to flow into the protected compartment through the vent, comprising: a plurality of S-shaped louvers each having an exterior end and an interior end, wherein each louver further comprises a hook portion at the interior end defining an inlet in the louver to form a ballistic hook for catching projectiles; and a plurality of inserts comprising a closeout permeable by projectiles, wherein each insert is affixed to the hook portion of a corresponding louver; wherein the S-shaped louvers are arranged in an overlapping configuration to define a plurality of circuitous paths through the vent between the louvers and to deny projectiles a linear path through the vent, wherein the inserts are positioned to enclose the inlet and the ballistic hook to maintain a continuous flow of air through the corresponding circuitous path.
 2. The ballistic grille of claim 1, wherein the exterior end of each louver comprises 1 tapered shape to facilitate the flow of the air into the circuitous paths.
 3. The ballistic grille of claim 1, wherein each closeout forms an enclosed air pocket within the corresponding inlet.
 4. The ballistic grille of claim 1, wherein each insert further comprises a foam core positioned within the corresponding inlet, wherein the foam core comprises a lower density material than the louver such that projectiles can penetrate the foam core.
 5. The ballistic grille of claim 4, wherein the foam core comprises a closed-cell foam material.
 6. The ballistic grille of claim 1, wherein the louver comprises a composite material combining a fibrous material and a matrix material.
 7. The ballistic grille of claim 6, wherein the fibrous material is selected from a group consisting of aramid, S2 glass fibers and combinations thereof.
 8. The ballistic grille of claim 6, wherein the fibrous material comprises about 60-80 wt % of the composite material and the matrix material comprises about 20-40 wt % of the composite material.
 9. The ballistic grille of claim 1, further comprising a plurality of hardened bars positioned proximate to the external ends of the louvers for fracturing and eroding incoming projectiles before the projectiles reach the louvers.
 10. The ballistic grille of claim 1, further comprising a honeycomb mesh positioned proximate to the internal ends of the louvers for capturing projectiles that ricochet through the circuitous paths.
 11. A louver for preventing projectiles from entering a protected vehicle compartment through an air supply vent while allowing air to flow into the protected compartment through the vent, comprising: an exterior end; an interior end having a hook portion defining an inlet in the louver to form a ballistic hook for catching projectiles; and an insert having a closeout permeable by projectiles enclosing the inlet and ballistic hook; wherein the louver comprises an s-shape such that the louver can be arranged in an overlapping configuration with other S-shaped louvers to define at least one circuitous path through the vent between the louvers and to deny projectiles a linear path through the vent; wherein the insert prevents the ballistic hook from disrupting the flow of air through the circuitous path.
 12. The louver of claim 11, wherein the exterior end comprises a tapered shape to facilitate the flow of the air into the circuitous path.
 13. The louver of claim 11, wherein the closeout forms an enclosed air pocket within the corresponding inlet.
 14. The louver of claim 11, wherein the insert further comprises a foam core positioned within the corresponding inlet, wherein the foam core comprises a lower density material than the louver such that projectiles can penetrate the foam core.
 15. The louver of claim 14, wherein the foam core comprises a closed-cell foam material.
 16. The louver of claim 11, wherein the louver comprises a composite material combining a fibrous material and a matrix material.
 17. The louver of claim 16, wherein the fibrous material is selected from a group consisting of aramid, S2 glass fibers and combinations thereof.
 18. The louver of claim 16, wherein the fibrous material comprises about 60-80 wt % of the composite material and the matrix material comprises about 20-40 wt % of the composite material.
 19. A method of preventing projectiles from entering an air supply vent for a protected compartment, comprising: positioning a plurality of S-shaped louvers in the vent, wherein each louver comprises a hook shape portion defining an inlet in the louver to form a ballistic hook for capturing projectiles; arranging the S-shaped louvers in an overlapping arrangement to define a plurality of circuitous routes through the vent for the passage of air and denying projectiles linear paths through the vent; and enclosing the inlet with a closeout permeable by a projectile to prevent the ballistic hook from disrupting the air flow through the circuitous route. 